(1) Field of the Invention
The present invention relates to an ultra-violet ray-reflecting fabric. More particularly, the present invention relates to a white moisture-permeable water-proof fabric having a very high ultraviolet ray-reflection efficiency and used for camouflaging goods or persons against detection during reconnaissance by the naked eye of ice fields or snow fields, by ultraviolet filter photography, and by various ultra-violet detectors used for military purposes.
Furthermore, this fabric can be used in the leisure field as a suntan-promoting mat having a high ultraviolet-reflection efficiency, and can be used, for example, on the beach for rapidly obtaining a better suntan.
(2) Description of the Related Art
Recently, military reconnaissance is carried out not only by the naked eye but also by using ultra-violet filter photography or various ultraviolet detectors. Accordingly, the development of an article-camouflaging or a personnel camouflaging sheet or clothing having an ultraviolet ray-reflection efficiency in the ultraviolet wavelength region equal or close to that of snow, is urgently required as a protection against such a reconnaissance using ultraviolet rays.
As the means for meeting this requirement, recently processing methods of imparting an ultraviolet ray-reflecting capacity to a fabric have been proposed. For example, Japanese Unexamined Patent Publication No. 62-169814 discloses an ultraviolet ray-reflecting material containing fine resin particles obtained by polymerizing a condensable triazine compound, and teaches that a white sheet obtained by incorporating the above-mentioned resin particles into a vinyl chloride resin or an acrylic rubber has an ultraviolet ray reflectance of 97 to 98% at a wavelength of 350 nm. Furthermore, Japanese Examined Utility Model Publication No. 63-24141 teaches that a synthetic fiber woven fabric having innumerable voids in the interior of the fiber has a reflectance of 69% at a wavelength of 360 nm. The former sheet has a composite structure comprising a substrate layer and an outer layer and the latter sheet has a single layer structure composed solely of the fiber. The sheet having a composite structure is characterized by an excellent water proofing and a very high ultraviolet reflectance, but is disadvantageous in that the softness is poor, the sheet has no air permeability or no moisture permeability, and the weight thereof is heavy. The single-layer sheet composed solely of the fiber has a light weight and a good softness, and is air-permeable and moisture-permeable, and thus this sheet is comfortable when worn in the form of clothing. Nevertheless, this sheet is disadvantageous in that the ultraviolet ray reflectance is not as high as that of the sheet having a composite structure and the waterproofing is poor. Accordingly, each of the above sheets has advantages and disadvantage, and thus the required performances have not been obtained therefrom.
In the leisure field, a sheet comprising a fibrous fabric substrate coated with an aluminum film is marketed as a suntan-promoting mat, and if this mat is used on the beach or the like, not only rays from the sun but also rays reflected from the mat spread below the body are effectively utilized for the suntanning, and therefore, a good suntan is rapidly obtained. This mat has an ultraviolet reflection efficiency of about 60% at a wavelength of 300 to 400 nm, but is disadvantageous in that the sheet per se becomes very hot when exposed directly to the rays of the sun, and thus even ultraviolet rays having a wavelength shorter than 320 nm, which are harmful to the skin, are reflected. Accordingly, an excessive heating must be prevented, even when exposed directly to the rays of the sun, whereby the reflection of ultraviolet rays having a wavelength of at least 320 nm is further increased while blocking harmful ultraviolet rays having a wavelength shorter than 320 nm, and thus a suntan-promoting mat which is more effective than the commercially available aluminum-coated mat, will be obtained.